BackgroundMounting evidence indicates that children who experience abuse and neglect are prone to chronic diseases and premature mortality later in life. One mechanistic hypothesis for this phenomenon is that early life adversity alters the expression or functioning of the glucocorticoid receptor (GR) throughout the course of life and thereby increases sensitivity to inflammatory stimulation. An exaggerated pro-inflammatory response is generally considered to be a key cause of postoperative cognitive dysfunction (POCD). The aim of this study was to examine the effects of early life adversity on cognitive function and neuroinflammation after sevoflurane anesthesia in adult rats and to determine whether such effects are associated with the epigenetic regulation of GR.MethodsWistar rat pups were repeatedly subjected to infant maternal separation (early life stress) from postnatal days 2–21. In adulthood, their behavior and the signaling of hippocampal pro-inflammatory factors and nuclear factor-kappa B (NF-κB) after sevoflurane anesthesia were evaluated. We also examined the effects of maternal separation (MS) on the expression of GR and the DNA methylation status of the promoter region of exon 17 of GR and whether behavioral changes and neuroinflammation after anesthesia were reversible when the expression of GR was increased by altering DNA methylation.ResultsMS induced cognitive decline after sevoflurane inhalation in the Morris water maze and context fear conditioning tests and enhanced the release of cytokines and the activation of astrocyte intracellular NF-κB signaling induced by sevoflurane in the hippocampus of adult rats. Blocking NF-κB signaling by pyrrolidine dithiocarbamate (PDTC) inhibited the release of cytokines. MS also reduced the expression of GR and upregulated the methylation levels of the promoter region of GR exon 17, and such effects were reversed by treatment with the histone deacetylase inhibitor trichostatin A (TSA) in adult rats. Moreover, TSA treatment in adult MS rats inhibited the overactivation of astrocyte intracellular NF-κB signaling and the release of cytokines and alleviated cognitive dysfunction after sevoflurane anesthesia.ConclusionsEarly life stress induces cognitive dysfunction after sevoflurane anesthesia, perhaps due to the aberrant methylation of the GR gene promoter, which reduces the expression of the GR gene and facilitates exaggerated inflammatory responses.

Dexmedetomidine has been reported to reduce mortality in septic rats. This study was designed to investigate the effects of dexmedetomidine on inflammatory reaction in lung tissues of septic rats induced by CLP. After induction of sepsis, the rats were treated with normal saline or dexmedetomidine (5, 10, or 20 μg/kg). The survival rate of septic rats in 24 h was recorded. The inflammation of lung tissues was evaluated by HE stain. The concentrations of IL-6 and TNF-α in BALF and plasma were measured by ELISA. The expressions of TLR4 and MyD88 were measured by western blotting. The activation of NF-κB in rat lung tissues was assessed by western blotting and immunohistochemistry. It was found that the mortality rate and pulmonary inflammation were significantly increased in septic rats. IL-6 and TNF-α levels in BALF and plasma, NF-κB activity, and TLR4/MyD88 expression in rat lung tissues were markedly enhanced after CLP. Dexmedetomidine (10 and 20 μg/kg) significantly decreased mortality and pulmonary inflammation of septic rats, as well as suppressed CLP-induced elevation of TNF-α and IL-6 and inhibited TLR4/MyD88 expression and NF-κB activation. These results suggest that dexmedetomidine may decrease mortality and inhibit inflammatory reaction in lung tissues of septic rats by suppressing TLR4/MyD88/NF-κB pathway.

Mobilization of mesenchymal stem cells (MSCs) is a promising strategy for tissue repair and regenerative medicine. The establishment of an appropriate animal model and clarification of the underlying mechanisms are beneficial to develop the mobilization regimens for therapeutic use. In this study, we therefore established a rat MSC mobilization model and investigated the related mechanisms, using continuous hypoxia as the mobilizing stimulus. We found that MSCs could be mobilized into peripheral blood of rats exposed to short-term hypoxia (2 days) and the mobilization efficiency increased in a time-dependent manner (2-14 days). Hypoxia-inducible factor-1α (HIF-1α) was upregulated during hypoxic exposure and was expressed continuously in bone marrow. Inhibition of HIF-1α expression by YC-1 remarkably reduced the number of mobilized MSCs, suggesting that HIF-1α is essential for hypoxia-induced MSC mobilization. Further, we investigated the potential role of HIF-1α target genes, vascular endothelial growth factor (VEGF), and stromal cell-derived factor-1α (SDF-1α). VEGF expression was elevated from day 2 to day 7 of hypoxia, stimulating an increase in bone marrow sinusoidal vessels and possibly facilitating the egress of MSCs. SDF-1α protein levels were increased in the peripheral blood of rats during MSC mobilization and promoted the migration of MSCs under hypoxic conditions in vitro. These results suggest that HIF-1α plays a pivotal role in hypoxia-induced MSC mobilization, possibly acting via its downstream genes VEGF and SDF-1α. These data provide a novel insight into the mechanisms responsible for MSC mobilization and may help in the development of clinically useful therapeutic agents.

Ketamine has been reported to cause neonatal neurotoxicity via a neuronal apoptosis mechanism; however, no in vivo research has reported whether ketamine could affect postnatal neurogenesis in the hippocampal dentate gyrus (DG). A growing number of experiments suggest that postnatal hippocampal neurogenesis is the foundation of maintaining normal hippocampus function into adulthood. Therefore, this study investigated the effect of ketamine on hippocampal neurogenesis. Male Sprague-Dawley rats were divided into two groups: the control group (equal volume of normal saline), and the ketamine-anesthesia group (40 mg/kg ketamine in four injections at 1 h intervals). The S-phase marker 5-bromodeoxyuridine (BrdU) was administered after ketamine exposure to postnatal day 7 (PND-7) rats, and the neurogenesis in the hippocampal DG was assessed using single- or double-immunofluorescence staining. The expression of GFAP in the hippocampal DG was measured by western blot analysis. Spatial reference memory was tested by Morris water maze at 2 months after PND-7 rats exposed to ketamine treatment. The present results showed that neonatal ketamine exposure significantly inhibited neural stem cell (NSC) proliferation, decreased astrocytic differentiation, and markedly enhanced neuronal differentiation. The disruptive effect of ketamine on the proliferation and differentiation of NSCs lasted at least 1 week and disappeared by 2 weeks after ketamine exposure. Moreover, the migration of newborn neurons in the granule cell layer and the growth of astrocytes in the hippocampal DG were inhibited by ketamine on PND-37 and PND-44. Finally, ketamine caused a deficit in hippocampal-dependent spatial reference memory tasks at 2 months old. Our results suggested that ketamine may interfere with hippocampal neurogenesis and long-term neurocognitive function in PND-7 rats. These findings may provide a new perspective to explain the adult neurocognitive dysfunction induced by neonatal ketamine exposure.

BackgroundThe restoration of damaged meniscus has always been a challenge due to its limited healing capacity. Recently, bone marrow-derived mesenchymal stem cells (BMSCs) provide a promising alternative to repair meniscal defects. However, BMSCs are not ideal chondroprogenitor cells for meniscus repair because they have a high propensity for cartilage hypertrophy and bone formation. Our hypothesis is that mesenchymal stem cells (MSCs) reside in meniscus maintain specific traits distinct from others which may be more conducive to meniscus regeneration.MethodsMSCs were isolated from bone marrow and menisci of the rabbits. The similarities and differences between BMSCs and MMSCs were investigated in vitro by a cell culture model, ex vivo by a rabbit meniscus defect model and in vivo by a nude rat implantation model using histochemistry, immunocytochemistry, qRT-PCR and western blotting.ResultsOur data showed that two types of MSCs have universal stem cell characteristics including clonogenicity, multi-potency and self-renewal capacity. They both express stem cell markers including SSEA-4, Nanog, nucleostemin, strol-1, CD44 and CD90.However, MMSCs differed from BMSCs. MMSC colonies were much smaller and grew more slowly than BMSC colonies. Moreover, fewer MMSCs expressed CD34 than BMSCs. Finally, MMSCs always appeared a pronounced tendency to chondrogenic differentiation while BMSCs exhibited significantly greater osteogenic potential, whatever in vitro and in vivo.ConclusionsThis study shows the similarities and differences between MMSCs and BMSCs for the first time. MMSCs are a promising source of mesenchymal stem cells in repairing meniscus defect.Electronic supplementary materialThe online version of this article (doi:10.1186/s12891-015-0511-8) contains supplementary material, which is available to authorized users.

Background: Peripheral nerve injuries that provoke neuropathic pain are associated with chronic inflammation and nervous lesions. The authors hypothesized that chronic neuropathic pain might be caused by chronic inflammation resulting from a nervous autoimmune reaction triggered by nerve injury. Methods: The authors observed chronic inflammation and neuropathic behaviors for up to 12 weeks after nerve injury in T lymphocyte-deficient nude mice and their heterozygous littermates. Lymphocyte proliferation and Schwann cell apoptosis were examined after coculture of each population with various neural tissues from normal rats and those with nerve injury. Result: Nude mice recovered faster and exhibited less thermal hyperalgesia after nerve injury compared to their heterozygous littermates. A large number of IL-17 + cells indicative of lymphocyte activation were found in the injured sciatic nerve and spinal cord (L4-6) of heterozygous littermates, but far fewer of these populations were found in nude mice. In vitro lymphocyte proliferation was enhanced after coculture with nerve tissues from normal rats compared to nerve tissue-free phosphate-buffered saline controls. In particular, coculture with sciatic nerve tissue enhanced proliferation by 80%, dorsal root ganglion by 46%, and spinal cord by 14%. Moreover, neural tissues from rats with nerve injury markedly increased the lymphocyte proliferation compared

Tendon stem cells (TSCs) may be used to effectively repair or regenerate injured tendons. However, the fates of TSCs once implanted in vivo remain unclear. This study was aimed to determine the feasibility of labeling TSCs with super-paramagnetic iron oxide (SPIO) nano-particles to track TSCs in vivo using MRI. Rabbit TSCs were labeled by incubation with 50 μg/ml SPIO. Labeling efficiency, cell viability, and proliferation were then measured, and the stemness of TSCs was tested by quantitative real time RT-PCR (qRT-PCR) and immunocytochemistry. We found that the labeling efficiency of TSCs reached as high as 98%, and that labeling at 50 μg/ml SPIO concentrations did not alter cell viability and cell proliferation compared to non-labeled control cells. Moreover, the expression levels of stem cell markers (Nucleostemin, Nanog, and Oct-4) did not change in SPIO-labeled TSCs compared to non-labeled cells. Both labeled and non-labeled cells also exhibited similar differentiation potential. Finally, labeled TSCs could be detected by MRI both in vitro and in vivo. Taken together, the findings of this study show that labeling TSCs with SPIO particles is a feasible approach to track TSCs in vivo by MRI, which offers a noninvasive method to monitor repair of injured tendons.

This is an Open Access article licensed under the terms of the Creative Commons AttributionNonCommercial 3.0 Unported license (CC BY-NC) (www.karger.com/OA-license), applicable to the online version of the article only. Distribution permitted for non-commercial purposes only. Previous studies have shown ketamine can alter the proliferation and differentiation of neural stem cells (NSCs) in vitro. However, these effects have not been entirely clarified in vivo in the subventricular zone (SVZ) of neonatal rats. The present study was designed to investigate the effects of ketamine on the proliferation and differentiation of NSCs in the SVZ of neonatal rats in vivo. Methods: Postnatal day 7 (PND-7) male SpragueDawley rats were administered four injections of 40 mg/kg ketamine at 1-h intervals, and then 5-bromodeoxyuridine (BrdU) was injected intraperitoneally at PND-7, 9 and 13. NSC proliferation was assessed with Nestin/BrdU double-labeling immunostaining. Neuronal and astrocytic differentiation was evaluated with β-tubulin III/BrdU and GFAP/BrdU double-labeling immunostaining, respectively. The expressions of nestin, β-tubulin III and GFAP were measured using Western blot analysis. The apoptosis of NSCs and astrocytes in the SVZ of neonatal rats was evaluated using nestin/caspase-3 and GFAP/caspase-3 double-labeling immunostaining. Results: Neonatal ketamine exposure significantly reduced the number of nestin/BrdU and GFAP/BrdU double-positive cells in the SVZ. Meanwhile, the expressions of nestin and GFAP in the SVZ from the ketamine group were significantly decreased compared those in the control group. Still, no double-positive cells for nestin/caspase-3 and GFAP/caspase-3 were found after ketamine exposure. In addition, the neuronal differentiation of NSCs in the SVZ was markedly promoted by ketamine with an increased number of β-tubulin III/BrdU double-positive cells and enhanced expression of β-tubulin III. These effects of ketamine on the NSCs in the SVZ often lasted at least 1 week after ketamine anesthesia. Conclusion: In the present study, it was demonstrated that ketamine could alter neurogenesis by inhibiting the proliferation of NSCs, suppressing their differentiation into astrocytes and promoting the neuronal differentiation of the NSCs in the SVZ of neonatal rats during a critical period of their neurodevelopment.